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Computer Aided Diagnosis of Appendicitis

The aim of this project is to build a learning medical expert system for computer aided diagnosis of acute abdominal pain, especially in the case of a suspected appendicitis (LEXMED). Since June 1999 LEXMED is being tested at the '14 Nothelfer Hospital' in Weingarten / Baden-Württemberg / Germany, with very good results. Additionally LEXMED is available (for physicians) on the internet (see 'registration' to obtain an account). It is easy to use and to access (free of charge).
Given the symptoms (maximal 14) of a patient with acute abdominal pain, LEXMED first gives the probability of four different diagnoses [inflammed appendicitis, perforated appendicitis, non specific abdominal pain (nsap), something else (other illness) ]. The second step delivers a proposal for a treatment (1 of 5 possibilities: operation, emergency operation, observe patient at home (out-patient), observe patient in hospital (in-patient), perform further examinations (it may be something else).


Its knowledge is based on a set of probability rules (500 at the moment) 400 of which stem from a database of 15.000 patient records (operations carried out on suspected appendicitis in 1995 in Baden-Württemberg / Germany) and 100 from our medical experts. The methods used to extract (uncertain) rules from data and to compile these rules together with those of the medical experts (to generate a complete probability model) are based on probability theory and its extension using the method of maximum entropy (for more details see the literature on our website). Due to its construction, new rules (from data or medical experts) could be compiled and used by LEXMED within minutes. From time to time we include new data (collected by our partners) and rules, which is the reason for calling it a learning expert system. The method of its construction is not just applicable for the diagnosis of abdominal pain or even restricted to the medical area. It could be applied for many different tasks of diagnosis in uncertain domains.


We plan to extend LEXMED to diagnose other causes of acute abdominal pain. To achieve this (but also for the current discussion) we are looking for interested physicians and other interested persons.


This project was funded by the "Ministerium für Wissenschaft, Forschung und Kunst" in Baden-Württemberg / Germany, in the group "Innovative Projekte" . The project started in November 1997 and was finished in December 1999. Ongoing research activities are being funded by the University of Applied Sciences Ravensburg-Weingarten.
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